On Meta-Wiki, enter "Help:Glo" in the search box. You get "Help:Global account" as a suggested result, but that page doesn't actually exist, nor has it been created-and-deleted in the past.
@TJones investigated the issue a bit; below is the summary of his findings:
<Trey314159> There's a redirect from "Global Account" to "Help:Unified_login". I would hypothesize that those get mixed up somehow (as in that's what I'd look at first to try to explain it), but I don't know.
<Trey314159> I have been able to reproduce the problem on enwiki, too. Searching for "Help:how to" suggests "Help:How to edit", but no such page exists. "How to edit" is a redirect to "Help:Editing".
<Trey314159> I had a chance to look further, and the problem you found is not limited to Help (as expected). "Wikipedia:Second account" has a similar set up ("second account" is a redirect to "Wikipedia:Sock puppetry", but "Wikipedia:Second account" doesn't exist).